/*
 * Copyright 2016 The gRPC Authors
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package io.grpc.examples.advanced;

import io.grpc.BindableService;
import io.grpc.Server;
import io.grpc.ServerBuilder;
import io.grpc.ServerServiceDefinition;
import io.grpc.examples.helloworld.GreeterGrpc;
import io.grpc.examples.helloworld.HelloReply;
import io.grpc.examples.helloworld.HelloRequest;
import io.grpc.stub.ServerCalls.UnaryMethod;
import io.grpc.stub.StreamObserver;

import java.io.IOException;
import java.util.logging.Logger;

import static io.grpc.stub.ServerCalls.asyncUnaryCall;

/**
 * Server that manages startup/shutdown of a {@code Greeter} server.
 *
 * <p>This is an advanced example of how to swap out the serialization logic.  Normal users do not
 * need to do this.  This code is not intended to be a production-ready implementation, since JSON
 * encoding is slow.  Additionally, JSON serialization as implemented may be not resilient to
 * malicious input.
 *
 * <p>If you are considering implementing your own serialization logic, contact the grpc team at
 * https://groups.google.com/forum/#!forum/grpc-io
 */
public class HelloJsonServer {
    private static final Logger logger = Logger.getLogger(HelloJsonServer.class.getName());

    private Server server;

    private void start() throws IOException {
        /* The port on which the server should run */
        int port = 50051;
        server = ServerBuilder.forPort(port)
                .addService(new GreeterImpl())
                .build()
                .start();
        logger.info("Server started, listening on " + port);
        Runtime.getRuntime().addShutdownHook(new Thread() {
            @Override
            public void run() {
                // Use stderr here since the logger may have been reset by its JVM shutdown hook.
                System.err.println("*** shutting down gRPC server since JVM is shutting down");
                HelloJsonServer.this.stop();
                System.err.println("*** server shut down");
            }
        });
    }

    private void stop() {
        if (server != null) {
            server.shutdown();
        }
    }

    /**
     * Await termination on the main thread since the grpc library uses daemon threads.
     */
    private void blockUntilShutdown() throws InterruptedException {
        if (server != null) {
            server.awaitTermination();
        }
    }

    /**
     * Main launches the server from the command line.
     */
    public static void main(String[] args) throws IOException, InterruptedException {
        final HelloJsonServer server = new HelloJsonServer();
        server.start();
        server.blockUntilShutdown();
    }

    private static class GreeterImpl implements BindableService {

        private void sayHello(HelloRequest req, StreamObserver<HelloReply> responseObserver) {
            HelloReply reply = HelloReply.newBuilder().setMessage("Hello " + req.getName()).build();
            responseObserver.onNext(reply);
            responseObserver.onCompleted();
        }

        @Override
        public ServerServiceDefinition bindService() {
            return io.grpc.ServerServiceDefinition
                    .builder(GreeterGrpc.getServiceDescriptor().getName())
                    .addMethod(HelloJsonClient.HelloJsonStub.METHOD_SAY_HELLO,
                            asyncUnaryCall(
                                    new UnaryMethod<HelloRequest, HelloReply>() {
                                        @Override
                                        public void invoke(
                                                HelloRequest request, StreamObserver<HelloReply> responseObserver) {
                                            sayHello(request, responseObserver);
                                        }
                                    }))
                    .build();
        }
    }
}
